This study explores how teachers in Swedish upper secondary schools perceive and use code-switching in the English Foreign Language (EFL) classroom. The aim is to understand teachers’ approaches, experiences, and reasoning behind the use of code-switching. Grounded in an interactional sociolinguistic framework, which views language choices as contextualization cues shaped by social and situational norms, the study adopts a qualitative research design, using semi-structured interviews with eight Swedish EFL teachers. The findings revealed that the teachers primarily use code-switching to clarify difficult content, ensure comprehension, and provide emotional support. Several of the participants emphasized the importance of code-switching in fostering a supportive learning environment, particularly during high-pressure situations, such as exams. However, concerns were also expressed about the potential overuse of code-switching into Swedish, which may limit the students’ exposure to English and hinder their language development. While code-switching was widely seen as a practical and time-saving strategy to meet the students’ needs, the results also highlight the importance of maintaining a balance. Teachers’ decisions to code-switch were found to be influenced by multiple interconnected factors covering student needs, classroom dynamics, pedagogical goals, and emotional contexts.